Bag normally means a container of things, due to the role of bags in travel, as well as the use of bags in fashion activities, leisure sports or business life, so the application of bag is very wide.
So far, products of many companies enable bags to be carried in horizontal direction or vertical direction, which is convenient to the consumers, but they also add a handle on the bag, such as haversack or luggage case. From the perspective of aesthetics, adding a handle usually makes it feel bulky and imbalanced, so some companies hide the added handle, or add two handles on one single bag, those methods are still impractical. From a practical view, adding two handles on one bag is a limited concept, it is not working or inconvenient when in use, because the opening of the bag can only be on one direction. Besides, pulling rod system couldn't work on two directions. The wheels of bag will be seen during horizontal movement.
A recent trend is to add one bag onto another bag, in this way, traveler feel more comfortable in carrying heavier things with a plastic clamp being used. However the plastic clamp often conflicts with the opening of the bag and causes inconvenience when using. Likewise a metal hook also has the same problem.
Some bags recently are added with net pocket, which is unstable and can carry light and small products only.